This invention pertains to charcoal fuel articles, and particularly those articles which are used for cooking food.
Charcoal fuel, for consumer use, is conventionally available in the form of pillow-shaped briquettes. These briquettes are formed in a molding operation which leaves the briquettes in the shape of a pillow, and yields a molded briquette surface which is relatively smooth. The edges of a conventional briquette may appear broken and irregular.
Conventional charcoal briquettes are typically used in charcoal cookers which are made specifically for that purpose. A standard charcoal cooker is a bowl shaped metal container approximately 18 to 22 inches in diameter having a fairly tight fitting bowl shaped lid, such that the closed cooker, in the use configuration, appears as more or less of a sphere. The lower receptacle portion of the cooker has a plurality of holes near its bottom to provide for incoming combustion air. Inside the receptacle, and above the holes, is a combustion grate, for holding charcoal fuel. Above the combustion grate is the cooking grate, at approximately the top of the receptacle portion of the cooker for holding food. Both the combustion grate and the cooking grate are removable. The lid portion of the cooker has a plurality of holes for venting hot gases from the cooker, with closure means for partially or totally closing the vent holes.
It is well known that, in order to ignite charcoal in a standard charcoal cooker, a substantial amount of heat must be applied to the charcoal; substantially more heat than is generated by a match. Typically charcoal is ignited by the use of an electric starter or by the application of a lighter fluid. Since the use of lighter fluid is the most common means of igniting conventional charcoal, the use of lighter fluid will be described herein with the understanding that similar discussion of other means of igniting conventional charcoal applies.
Typically, a mass of charcoal briquettes is arranged in a random stack in the charcoal cooker, and lighter fluid is applied from the lighter fluid container. One typically recommended amount of material for use is the combination of 4 lbs. of charcoal briquettes and 4 ounces of lighter fluid.
Typical problems encountered with conventional charcoal briquettes pertain mostly to the ignition phase. One of these problems is that the compacted, molded surface of the briquette is less porous than the body of the briquette, as a whole, and impedes the body of the charcoal briquette from absorbing the lighter fluid as quickly as desired. Thus, the user will observe the rate of absorption of fluid and adjust the rate of application of lighter fluid accordingly, lest the fluid run off the surface of the briquettes and be spilled to the bottom of the cooker, where it is not so efficiently used.
After the lighter fluid has been applied to the random stack of briquettes, the stack is ignited with a match. The match ignition ignites the lighter fluid in and on the briquettes. The lighter fluid burns with a substantially yellow flame. As it burns, the heat from its burning raises the temperature of the charcoal briquettes. As the temperature of the charcoal rises, the charcoal itself is ignited and burns, substantially without flame, but with a radiant glow accompanied with a surface covering of ash, which appears shortly after the ignition of the charcoal. By the time the lighter fluid has been consumed, the charcoal should be fully capable of sustaining combustion.
For purposes of this description, there are three phases to the process of igniting charcoal. The first phase is the ignition and burning of the lighter fluid, which is characterized by a typically yellow flame. The second phase begins when combustion of the charcoal becomes self-sustaining. The third and final phase of ignition is reached when heat flux received at the cooking surface reaches an amount sufficient for cooking food. As used herein, heat usable and adequate for cooking food means an instantaneous heat flux of at least about 1500 Btu/ft.sup.2 -hr for slow simmering and at least about 3000 Btu/ft.sup.2 -hr for quick frying received at the cooking surface when the igniting charcoal has been spread out in the cooking configuration.
It is highly desirable that the self-sustaining burning of the charcoal (phase 2) begin before the lighter fluid is completely consumed in phase 1 of the ignition, to ensure continuity of ignition. If the lighter fluid is all consumed before self-sustaining burning is achieved, the ignition sequence falters and a sustained burn is not achieved. With conventional charcoal briquettes, there is substantial difficulty in consistently achieving a self-sustaining burning of charcoal with every ignition without use of an inordinate amount of lighter fluid.
If too much lighter fluid is used, then cooking of food may be delayed to allow for burning off of the excess lighter fluid before cooking of food is begun. It is not particularly desirable to cook food before the lighter fluid has been all consumed, as the lighter fluid itself, and the fumes from burning it, are not particularly advantageous for use in cooking food. Once the charcoal has been adequately ignited to provide heat adequate for cooking food, the stack of charcoal is typically spread out to generally cover the combustion grate for the cooking process. Another problem with conventional charcoal briquettes is that a larger amount of charcoal than is needed for the cooking phase (phase 3) is typically used in order to ensure a successful ignition. In addition to being wasteful of the charcoal, the heat output from this larger amount may be so great as to burn the food.
A significant problem with conventional charcoal is that the ignition may be incomplete by the time the lighter fluid has all been consumed. In this event, additional lighter fluid may be added to the partially ignited stack of briquettes, whereby a dangerous flash fire may arise from the partially ignited stack of briquettes as the lighter fluid is being added. This has, of course, the potential risk of causing flame burns to the user.
Typical ignition time for conventional charcoal briquettes to generate enough heat to cook is on the order of 20 to 30 minutes. This time may vary substantially, depending on the number and severity of problems encountered in igniting the charcoal.
One solution that has been commercialized is to impregnate the charcoal with lighter fluid when it is manufactured; and to sell it as an impregnated fuel, not requiring the use of additional lighter fluid. This approach to the problem does provide a partial solution, but it also presents some difficulties. Since the lighter fluid is flammable and vaporizable, the packaging must be substantially vapor impermeable in order to contain the impregnated fluid. Even if the package is vapor impermeable, when the package is opened, a substantial amount of vapor is released to the atmosphere. Further, the impregnated briquettes should not be enclosed in a hot grill for any period of time without air, as a flash fire may erupt when the hot cooker is opened and air is admitted. In addition, since the lighter fluid is uniformly impregnated into the briquettes, it does not completely burn off before the cooking phase starts, but rather is present for a substantial period of the cooking phase. The presence of the lighter fluid during the cooking phase results in lighter fluid vapors and combustion gases from the lighter fluid being in contact with the food. This is detrimental both from the standpoint of taste and possible undesirable chemicals.
It is an object of this invention to provide an improved charcoal fuel article which ignites more easily, and reaches cooking temperature more quickly, than conventional charcoal fuel articles.
It is another object of the invention to provide a charcoal fuel article which, pound for pound, delivers to the cooking grate more heat usable and adequate for cooking food.
It is yet another object of the invention to provide a charcoal fuel article which has greater surface porosity.